In a wireless communication system such as a Wideband Code Division Multiple Access (WCDMA) system, Mobile Stations (MSs) operating in the system negotiate a certain Quality of Service (QoS) with the system before they are granted a dedicated data channel. The negotiation process may differ from one particular system to another, however, common to all communication systems is the fact that most service request negotiations include a repetition of information such as data rates, spreading factors, mean packet delay requirements, packet loss, etc.
An MS commencing a negotiation for service does not guarantee a service request will be granted, which is certainly true in congested geographic areas. In addition, the time it takes a MS to realize success or failure in a service negotiation is usually long enough to cause wasted battery life for the MS and an overall increase in system noise due to the number of service requests that ultimately will not be successful that are transmitted.
A typical prior art service request negotiation in a Universal Mobile Telephone Service (UMTS) WCDMA system is shown in FIG. 1. In a UMTS system, when a MS requests a particular service, it will begin the service negotiation by sending an access attempt in the form of a Random Access Channel (RACH) preamble 102 to the system. Each access preamble 102 in the example shown in FIG. 1 is made up of a signature repeated 256 times to form a 4096 bit wide preamble frame 104. The signature is selected randomly for each access preamble from a group of signatures stored in the MS. The MS receives the set of available signatures during system initialization or registration of the MS into the system from the communication system. The preamble corresponds to a signature S that includes 256 repetitions of a length 16-signature (Sx, 15 to Sx, 0). In the UMTS system, the signature is from a set of 16 Hadamard codes of length 16. There exist a total of 16 signatures to randomly choose from for the RACH preamble transmission 102 for each RACH channel, and there are a maximum of 16 RACH channels, corresponding to the maximum available preamble scrambling codes. What distinguish the preamble transmission of two different mobile stations on the uplink path is the unique scrambling codes assigned for each user by the base station (cell site).
Depending on the MS's access class, it can use certain time slots (“access slots”) 106 for its preamble transmissions. If the system properly receives the access request, it will acknowledge it by resending the same signature as a downlink acquisition indicator (AI) 108 on the Acquisition Indicator Channel (AICH) by the base station. The MS decodes the system acknowledgment, and proceeds to send its RACH message 110 to the system.
In FIG. 2 there is shown a prior art service negotiation between the communication system and an MS. In Step 202, the MS sends an uplink RACH 202 followed by a response by the system in the downlink path. This RACH process takes approximately 300 milliseconds (ms) to complete as shown. A Radio Resource Control (RRC) signaling 204 follows the RACH signaling 202. If the system successfully decodes the RACH message, it will inform the MS of the establishment of the signaling link. At this point, the MS initiates its service request 206, followed by authentication 208 and identity check 210 signaling sequences. The overall service negotiation process takes approximately 5 to 8 seconds to complete. At the end of the negotiation, the MS realizes whether or not the system is willing to grant it a channel for the service requested.
As more and more services that require faster access times to system resources (e.g., real time services like dispatch calls, etc.) are introduced, a need exists for a way of accelerating the service negotiation process in order to provide faster system access times and help improve some of the problems previously noted.